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O (.o)

.o file signature | application/octet-stream

Executable and Linkable Format[25]

Safe

Magic Bytes

Offset 0
7F 45 4C 46

Sources: Wikipedia

Extension

.o

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

Safe

Validation Code

How to validate .o files in Python

Python 
def is_o(file_path: str) -> bool:
    """Check if file is a valid O by magic bytes."""
    signature = bytes([0x7F, 0x45, 0x4C, 0x46])
    with open(file_path, "rb") as f:
        return f.read(4) == signature

How to validate .o files in Node.js

Node.js 
function isO(buffer: Buffer): boolean {
  const signature = Buffer.from([0x7F, 0x45, 0x4C, 0x46]);
  return buffer.subarray(0, 4).equals(signature);
}

How to validate .o files in Go

Go 
func IsO(data []byte) bool {
    signature := []byte{0x7F, 0x45, 0x4C, 0x46}
    if len(data) < 4 {
        return false
    }
    return bytes.Equal(data[:4], signature)
}

API Endpoint

GET /api/v1/o
curl https://filesignature.org/api/v1/o

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .o file?

A .o file is a O file. Executable and Linkable Format[25]

What are the magic bytes for .o files?

The magic bytes for O files are 7F 45 4C 46 at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .o file?

To validate a .o file, read the first bytes of the file and compare them against the known magic bytes (7F 45 4C 46) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .o files?

There is no officially registered MIME type for .o files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .o files?

O (.o) files are generally safe to open. They are classified as low risk because they primarily contain data rather than executable code. However, always ensure files come from a trusted source.